Method for manufacturing filter member

ABSTRACT

A principal object of the present invention is to provide a method for manufacturing a filter element having a resin-molded frame, which permits to easily form the resin-molded frame, even when the filter has a complicated shape. The above-mentioned object can be achieved by providing the method for manufacturing the filter element, which is characterized by comprising the steps of: semi-curing resin in a prescribed shape to prepare a semi-cured resin; inserting forcedly at least one part of a filter into the semi-cured resin; and curing the semi-cured resin into which the at least one part of the filter has been forcedly inserted.

This application is a 371 of international application No.PCT/JP00/03897, filed on Jun. 15, 2000, which designated the UnitedStates of America.

TECHNICAL FIELD

The present invention relates to a method for manufacturing a filterelement, in which a retaining member and the other members such as asealing member made of resin are secured to a filter.

BACKGROUND OF THE INVENTION

In general, a filter such as an air filter and an oil filter is securedto a member having a high rigidity, such as a retaining member tocompose a filter element to be used. Because the filter as manufacturedis formed of material having a relatively low rigidity such as filterpaper, and it is therefore difficult to mount such a filter by itself tothe other member or provide a sufficient air-tightness between thefilter and the other member.

In view of easy formability, resin is normally used for forming theabove-mentioned member having a high rigidity. An insert injection isoften applied to secure the rigid member on the filter.

Such an insert injection can be applied to manufacture of the filterhaving a simple shape. However, the insert injection may not be appliedto manufacture the filter having a complicated shape. More specifically,some consideration is needed to bring the filter into contact with themold so as to prevent resin from spreading over any portions of thefilter, excluding its portions to which resin body is to be formed. Thecomplicated shape of the filter however leads to complication of themold. There may be a case in which the mold cannot be formed due to itscomplexity, causing a problem. When an attempt is made to form aresin-molded body on each of the opposite ends of a tubular filterhaving a complicated shape such as a chrysanthemum shape by the insertinjection, a mold placed in the filter cannot be removed, thus causing aproblem. It is substantially impossible to apply the insert injection tothe opposite ends of such a filter.

DISCLOSURE OF THE INVENTION

An object of the present invention, which was made in view of theabove-mentioned problems, is therefore to provide a method formanufacturing a filter element having a resin-molded frame, whichpermits to easily form the resin-molded frame, even when the filter hasa complicated shape.

In order to attain the aforementioned object, a method of the presentinvention for manufacturing a filter element, comprises the steps of:

semi-curing resin in a prescribed shape to prepare a semi-cured resin;

inserting forcedly at least one part of a filter into said semi-curedresin; and

curing said semi-cured resin into which said at least one part of saidfilter has been forcedly inserted.

According to the present invention, a part of the filter is insertedinto the semi-cured resin, and then, the semi-cured resin is completelycured. As a result, a mold, which provides a prescribed shape of resinduring semi-curing the resin, suffices. A complicated shape of thefilter does not lead to complication of the mold. It is thereforepossible to form a molded body of resin, leading to an easy manufactureof the filter element at a low cost, even when the filter has acomplicated shape.

The filter element of the present invention may preferably be applicablein case where the filter is a tubular filter and at least one part ofthe filter, which is to be forcedly inserted into the semi-cured resin,is opposite ends of the tubular filter. It has been substantiallyimpossible to apply the insert injection to the opposite ends of thetubular filter, especially the tubular filter having the complicatedshape to form a molded resin. It is therefore possible to apply thepresent invention to formation of the molded resin on the opposite endsof the tubular filter, thus putting the technical effects of the presentinvention to practical use.

In the method of the present invention for manufacturing the filterelement, the above-mentioned resin and material for the filter maypreferably be formed of same material. The feature that theabove-mentioned resin, i.e., a member (such as an outer frame), which isformed on a part of the filter and has a high rigidity, and the materialfor the filter are formed of the same material, makes it unnecessary toseparate the filter from the outer frame or the other structuralcomponent, when the filter element is recycled. It is therefore possibleto recycle the filter element as it is, thus leading to an effectiverecycling system.

Another object of the present invention is to provide the filterelement, which is manufactured by carrying out the above-mentionedmethod for manufacturing the filter element. A mold for such a filterelement is simpler than a mold for the conventional filter element inwhich the molded resin is formed by the insert injection, thus reducingthe manufacturing cost of the mold. No time is required to remove themold, providing advantages in costs. In addition, it is possible to formthe resin frame on the filter having a complicated shape such as achrysanthemum shape so as to provide the filter element in whichsupporting members made of resin are formed on the opposite ends of thefilter, although such a formation of the resin frame cannot be performedby the conventional technique.

Further another object of the present invention is to provide a mold formanufacturing a filter element, comprises:

a supporting member for supporting a filter so that at least one part ofsaid filter is exposed; and

a semi-curing mold member for semi-curing resin in a prescribed shape,said semi-curing mold section having a holding section for holding atleast a semi-cured resin and a removable section, which is removed toexpose at least one part of said semi-cured resin, said removablesection being disposed between an exposed part of said filter and saidholding section, and said holding section being disposed so that saidexposed part of said filter comes into contact with an exposed-part ofsaid semi-cured resin, after removal of said removable section.

According to such a mold, it is possible to insert quickly the part ofthe filter into the semi-cured resin during semi-curing the resin, toform the molded resin, even when the resin has a relatively short curingtime. More specifically, resin is first supplied into the semi-curingmold member. Then, the resin is semi-cured into a semi-cured state.After completion of the semi-curing step, the removable section of thesemi-curing mold member is removed. Removal of the removable sectioncauses the part of the filter, which is exposed from the holdingsection, is placed in a position where the part of the filter can comeinto contact with the semi-cured resin, which has been exposed throughthe removal of the removable section. Then, the part of the filter,which is exposed from the holding section, is inserted quickly into thesemi-cured resin as exposed. The semi-cured resin is then curedcompletely. As a result, the molded resin can be formed on the part ofthe filter in a short period of time. It is therefore possible to easilymanufacture the filter element with the use of the mold of the presentinvention, even when the resin has a relatively short curing time.

The method of the present invention for manufacturing the filter elementis characterized by comprising the steps of: semi-curing the resin inthe prescribed shape to prepare the semi-cured resin; inserting forcedlyat least one part of the filter into the semi-cured resin; and curingthe semi-cured resin into which the at least one part of the filter hasbeen forcedly inserted. The mold suffices to semi-cure the resin in theprescribed shape, leading to the simple structure, even when the filterhas a complicated shape. It is therefore possible to form the moldedresin on the filter, thus providing effects of manufacturing easily thefilter element at a low cost, even when the filter has a complicatedshape.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematic sectional view illustrating an example of a mold formanufacturing a filter element, which is used in the method of thepresent invention for manufacturing the filter element;

FIG. 2 is a schematic view illustrating an example of a manufacturingapparatus, which is used in the method of the present invention formanufacturing the filter element; and

FIG. 3 is a descriptive view illustrating an example of the steps of themethod of the present invention for manufacturing the filer element.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, description will be given in detail below of the method of thepresent invention for manufacturing a filter element.

The method of the present invention for manufacturing the filter elementis characterized by comprising the steps of: semi-curing resin in aprescribed shape to prepare a semi-cured resin; inserting forcedly atleast one part of a filter into the semi-cured resin; and curing thesemi-cured resin into which the at least one part of the filter has beenforcedly inserted.

First, description will be given of the first step, i.e., the step forsemi-curing the resin in a prescribed shape. The step for semi-curingthe resin in the prescribed shape is conducted by pouring the resin intoa metallic mold having a cavity with the prescribed shape andsemi-curing it, although the present invention is not limited only tosuch features. The conventional metallic molding method such as aninjection molding and a casting can be applied to the above-mentionedstep. The suitable molds for the respective molding methods areapplicable as the mold used in the above-mentioned step. The metallicmold may be completely closed or opened on the upper side. It ispreferable to use the metallic mold described later for manufacturingthe filter element in the present invention, in view of effectivenessand operability of the metallic mold.

There is used, as the resin to be used, resin generally used to form anouter frame of the filter. There may be used any kind of resin, whichcan be semi-cured, for example, thermosetting resin such as phenolresin, melamine resin and polyurethane resin, and thermoplastic resinsuch as polyethylene, polypropylene, polyvinyl chloride, acrylonitrilebutadiene styrene resin, and (polyolefin, polyurethane or polyester)thermoplastic elastomer (TPE).

In the present invention, it is preferable that the above-mentionedresin and material for forming the filter are formed of the same resin.The above-mentioned feature that the material for forming an outerframe, which has a high rigidity, and the material for forming thefilter are formed of the same material, makes it unnecessary to separatethe filter from the outer frame, when the filter element is recycled. Itis therefore possible to recycle the filter element as it is, thusleading to an effective recycling system.

With respect to the resin, which is applicable in view of the fact thatthe above-mentioned resin and the resin for forming the filter areformed of the same material, thermoplastic resin is preferable. Morespecifically, there may be included polyester, polyamide, polypropylene,polyethylene, acetylcellulose, acryl and polyvinyl chloride fiber. Anykind of material, which can be used as both the fiber material and themoldable resin, may be used.

In the present invention, polyester and polyamide, which have widelybeen used as the moldable resin and material for forming the filer andare low-priced, are especially preferable. Polypropylene andpolyethylene, which have widely been used as the moldable resin andmaterial for forming a mesh used for the filter placed in a tank and arelow-priced, are also preferable.

With respect to the semi-curing of the resin, in case where thethermosetting resin is used, selection of the resin having a relativelylong curing time makes it possible to obtain the resin in the semi-curedstate in the middle of a curing reaction of the resin. In case where thethermoplastic resin is used, the resin in the semi-cured state can beobtained by making adjustment of temperature of the metallic mold tomaintain a relatively long cooling period of time, after pouring theliquefied resin into the metallic mold.

The above-mentioned prescribed shape means the shape that which isrequired for the resin, which has been cured completely. If the resingoes from the semi-cured state to the cured state to cause change inshape such as shrinkage of resin, the above-mentioned shape includessuch change. Consequently, the above-mentioned prescribed shape meansthe shape of the frame and/or the other structural components of thefilter element as the finished product.

In the second step, a part of the filter is forcedly inserted into thesemi-cured resin. The “part” of the filter means its part on which themolded resin is formed. In the preferable embodiment, the part of thefilter means the end of the filter, on which a supporting member or asealing member is provided. In the most preferable embodiment, the partof the filter means the opposite ends of the filter.

In such a second step, the above-mentioned part of the filter isforcedly inserted into the semi-cured resin. In case where the moldedresin is formed on each of the opposite ends of the filter, there may becarried out the steps of: inserting forcedly the one end of the filterinto the semi-cured resin; curing the semi-cured resin; insertingforcedly the other end of the filter into the other semi-cured resin;and curing the other semi-cured resin. Alternatively, the opposite endsof the filter may be forcedly inserted simultaneously into the separatesemi-cured resins, respectively, and these semi-cured resins may becured completely.

The filter element of the present invention includes any type of thefilter element such as the filter element used in a fluid filter, i.e.,a fuel filter and an air filter, so long as the resin is used as theouter frame and/or the other structural components. The filter may haveany shape such as a panel-shape, a roll-shape and a tubular shape.Applying the present invention to the filter having the complicatedshape, to which the conventional insert injection cannot be applied, canfully provide the effects of the present invention, leading topreferable results. It is particularly preferable to apply the presentinvention to the tubular filter having the complicated shape such as achrysanthemum shape.

In the present invention, the semi-cured resin into which the part ofthe filter has been forcedly inserted is finally cured completely. Thecuring conditions depend on the resin to be used. In case where thethermosetting resin is used, heat may be applied to the resin to causecontinuously the curing reaction. In case where the thermoplastic resinis used, the metallic mold may be cooled to cure the resin.

Now, description will be given of the mold for manufacturing the filterelement, which is suitably applicable to the method of the presentinvention for manufacturing the filter element. The mold of the presentinvention for manufacturing the filter element is characterized bycomprising: a supporting member for supporting a filter so that at leastone part of said filter is exposed; and a semi-curing mold member forsemi-curing resin in a prescribed shape, said semi-curing mold sectionhaving a holding section for holding at least a semi-cured resin and aremovable section, which is removed to expose at least one part of saidsemi-cured resin, said removable section being disposed between anexposed part of said filter and said holding section, and said holdingsection being disposed so that said exposed part of said filter comesinto contact with an exposed part of said semi-cured resin, afterremoval of said removable section.

The above-mentioned mold will be described in detail below withreference to the drawings. FIG. 1 illustrates an example of the mold ofthe present invention for manufacturing the filter element. The mold 1for manufacturing the filter element is composed of a supporting member3 for supporting the filter 2 and a semi-curing mold member 4 forsemi-curing the resin in the prescribed shape.

In the example, the supporting member 3, which is designed to supportthe tubular filter 2, is obtained by forming a groove into which thefilter 2 can be inserted, on a cylindrical material. When the filter 2is inserted in the supporting member 3, the filter 2 is supported sothat the one end of the filter is exposed. The supporting member 3 ofthe present invention may have any structure so long as it supports thefilter so that the filter is partially exposed. The supporting member 3may have the groove, which has the similar shape to the shape of thefilter, as shown in FIG. 1. The supporting member 3 may have astructure, which catches a part of the filter so that the opposite endsof the filter are exposed. The principal function of the supportingmember is to support the filter. Accordingly, even in a case where thesupporting member has the groove into which the filter is to be insertedas shown in FIG. 1, the groove does not need to precisely coincide withthe shape of the filter, but may have a rough shape by which the filtercan be supported. It is therefore possible to easily manufacture themold at a low cost in comparison with a mold, which is used in theinsert injection.

In the mold 1 as shown in FIG. 1 for manufacturing the filter element,the semi-curing mold member 4, which is composed of a holding section 5and a removable section 6, is placed on the supporting member 3. Theholding section 5 of the semi-curing mold member 4 has a ring-shapedgroove 7, by which the semi-cured resin is formed in accordance with theshape of the end of the above-mentioned tubular filter 2. The holdingsection 5 also has a gate 8 formed thereon, for supplying molten resininto the above-mentioned groove 7. The removable section 6 serving asthe other structural component of the mold 1 for manufacturing thefilter element comes on its upper surface into contact with the holdingsection 5 so as to liquid-tightly close the groove 7. The removablesection 6 is placed on the supporting member 3 so as to be removableafter the groove 7 is filled with the resin and then the resin issemi-cured. Even when the removable section 6 is removed, the semi-curedresin is held in the groove 7.

In the example, the semi-curing mold member 4 is composed of twostructural parts, i.e., the holding section 5 and the removable section6. The present invention is not limited only to such a structure. Thesemi-curing mold member may be divided into three or more parts so longas it has the holding section for holding the semi-cured resin and theremovable section, which is removed to expose the part of the semi-curedresin. Here, the “holding the semi-cured resin” means to hold thesemi-cured resin without moving after removal of the removable section,and the above-mentioned “holding” means to hold the semi-cured resinuntil the part of the filter is forcedly inserted into the semi-curedresin as exposed, after the removal of the removable section.

In the example as shown in FIG. 1, the groove 7 is filled with the resinand the removable section 6 is then removed after the supplied resin issemi-cured. During such a removal operation, the groove 7 for holdingthe semi-cured resin is placed so as to face the upper end of the filter2 supported by the supporting member 3. Moving down simply the holdingsection 5 causes the upper end of the filter 2 to be forcedly insertedinto the semi-cured resin in the groove 7.

No example of the method of the present invention for manufacturing thefilter element, utilizing the above-mentioned mold 1 for manufacturingthe filter element will be described with reference to FIGS. 2 and 3.FIG. 2 is a schematic view illustrating the example of the manufacturingapparatus, which is used in the manufacturing method of the presentinvention. The manufacturing apparatus 9 comprises a turntable 11, onwhich a mold unit 10 having two molds 1 for manufacturing the filtermember can be placed and which is turnable; and a supplying device 12for supplying the resin into the mold unit 10. The turntable 11 turns tomove the mold unit 10, which are placed on the turntable 11, between aformation/insertion area 13 in which the steps of supplying the resinand curing it are carried out and an insertion/reversing area 14 inwhich the filter is inserted and reversed.

The manufacturing method utilizing the above-mentioned manufacturingapparatus 9 will be described with reference to FIGS. 2 and 3. First,the filter 2 is inserted into the groove of the left-hand supportingmember 3 of the mold unit 10, which is placed in the insertion/reversingarea 14, so as to hold the filter 2 therein (see FIG. 3(a)). Then, theabove-mentioned semi-curing mold section 4 is placed on the supportingmember 3 (see FIG. 3(b)). Then, turning the turntable 11 causes the moldunit 10 to move into the formation/insertion area 13. The molten resinis supplied into the left-hand semi-curing mold section 4 of the moldunit 10 as moved, from the supplying device 12. The removable section 6is removed after the resin in the mold unit 10 is semi-cured (see FIG.3(c)). Then, the upper end of the filter 2 is forcedly inserted into thesemi-cured resin in the groove 7 of the holding section 5. Then, themold unit 10 is cooled to cure the semi-cured resin completely. Theturntable 11 turns to move again the mold unit 10 into theinsertion/reversing area 14. The holding section 5 of the mold unit 10as moved is removed and the filter 2 supported therein is taken out. Thefilter 2 thus pulled out is turned upside down and then inserted intothe groove of the right-hand supporting member 3 so that the end of thefilter 2, on which the molded resin 15 has been formed, is directeddownward (see FIG. 3(d)). In this case, the new filter may be insertedinto the groove of the left-hand supporting member to carry out thesteps for manufacturing the next filter element. After the filter 2 isturned upside down and inserted, the semi-curing mold section 4 isplaced on the supporting member 3 (see FIG. 3(e)). The turntable 11turns to move the mold unit 10 into the formation/insertion area 13. Theresin is inserted into the groove 7 of the semi-curing mold section 4with the use of the supplying device 12 in the same manner as describedabove. The resin is then semi-cured. The removable section 6 is removedso that the other end of the filter 2, on which the molded resin 15 hasnot as yet been formed, is forcedly inserted into the semi-cured resin(see FIG. 3(f)). After the resin is cured completely, the turntable 11turns to move the mold unit 10 into the insertion/reversing area 14.Then, the filter 2 is taken out from the supporting member 3. The filterelement 16 having the molded resin 15 on the opposite ends thereof isobtained in this manner (see FIG. 3(g)).

The present invention is not limited only to the above-describedembodiments. The embodiments are merely described by way ofillustration. Any invention, which has the structure based onsubstantially the same technical idea as that defined in claims andprovides the same effects, is included in the technical scope of thepresent invention.

In the above description, the mold for molding the resin is described asa metallic mold. The mold is however not limited only to the metallicmold, and may be a mold made of resin.

What is claimed is:
 1. A method for manufacturing a filter element,comprising the steps of: supporting a filter so that at least one partof said filter is exposed; semi-curing resin in a prescribed shape toprepare a semi-cured resin through a removable section in a place, whichis apart from the exposed part of said filter so as to face the exposedpart thereof, and hold it; removing the removable section and bringingsaid semi-cured resin into contact with the exposed part of said filter,to insert forcedly the part of said filter into said semi-cured resin;and curing said semi-cured resin into which the part of said filter hasbeen forcedly inserted.
 2. The method for manufacturing a filter elementas claimed in claim 1, wherein: said filter is a tubular filter, andsaid at least one part of said filter, which is to be forcedly insertedinto said semi-cured resin, is opposite ends of said tubular filter. 3.The method for manufacturing a filter element as claimed in claim 1,wherein: said resin and material for said filter are formed of samematerial.
 4. A mold for manufacturing a filter element, comprising: asupporting member for supporting a filter so that at least one part ofsaid filter is exposed; and a semi-curing mold member for semi-curingresin in a prescribed shape, said semi-curing mold section having aholding section for holding at least a semi-cured resin and a removablesection, which is removed to expose at least one part of said semi-curedresin, said removable section being disposed between an exposed part ofsaid filter and said holding section, and said holding section beingdisposed so that said exposed part of said filter comes into contactwith an exposed part of said semi-cured resin, after removal of saidremovable section.